Geotechnical Characterization of soils for Use as Landfill Liner: A case study of soil samples from the Paynesville Sandstone and Farmington River Formation, Liberia

Abstract

In Liberia, waste management is one of the main challenges faced by municipal authorities, environmental technicians and public health practitioners in their quest to maintain a clean, safe and healthy environment. The construction and operation of a sanitary landfill ensures adequate waste management and, by extension, the protection of both the environment and human receptors. This study presents the results of geotechnical investigations conducted on soils from two sedimentary units of Liberia: Paynesville Sandstone and Farmington River Formation. The intent of the study was to assess the suitability of the soil for use as landfill liner. Three soil samples were collected from each of the two sedimentary units and, using B.S 1377 (1990), soils characteristics such as particle size distribution, permeability, liquid limit, plastic limit, plasticity index and hydraulic conductivity were measured and presented as mean values. Hydraulic conductivity of a sanitary landfill liner is the most important parameter to consider in materials selection. The results of hydraulic conductivity obtained from the study showed that only the samples from Farmington River Formation met the USEPA (1994) and CGRM (2007) requirement of ≤ 1x10-9 m/sec suitable for use as landfill liner. The mean soil permeability results for the Paynesville Sandstone and Farmington River Formation were 2.5 mL/hr and 0.05 mL/hr respectively; implying that the samples from the Paynesville Sandstone are more permeable and, thus, more susceptible to leaching and groundwater contamination if used as a bottom liner in a landfill design. Based on the findings of this research, it can be concluded that the sample from the Farmington River Formation is more suitable for use as a natural material for landfill liner. The quality of the sample should, however, be improved by addition of small amounts of bentonite.

Evaluation of Soil and Groundwater Quality at the New Georgia Open Dumpsite in Caldwell, Liberia

“…Study of soil quality in the study area revealed predominantly sand and silt type of soil. Sandy soils are known to have high permeability, which results in high permeation rates and good drainage [15]. A preliminary survey of about 100 households in the study community showed that about 60% of the residents use groundwater from boreholes for drinking and domestic purposes (Figure 1).…”